Electric motor switching mechanism



June 28, 1949 WAHLBERG 2,474,707

ELECTRIC MOTOR SWITCHING MECHANISM Filed Jan. 29, 1944 2 Sheets-Sheet 1[08 001! MOTOR UNI T INVENTOR.

BY Jaw/4M June 28, 1949. E. WAHLBERG 2,474,707

ELECTRIC MOTOR SWITCHING MECHANISM Filed Jan. 29, 1944 7 2 Sheets-Sheet2 INVENTOR. ,4; A

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Patented June 28, 1949 UNITED STATES PATENT OFFICE ELECTRIC MOTOR,SWITCHING MECHANISM Eric C. Wahlberg, Stamford, Conn., assignor toElectrolux Corporation, Old Greenwich, Conn., a corporation of DelawareApplication January 29, 1944, Serial No. 520,261

2 Claims. 1

My invention relates to electric switching mechanism and moreparticularly to a device of this type havin means whereby an electriccircuit or circuits therethrough may be altered, for instance by amanual operation, together with means, such as an electric motor, forsubsequently restoring the circuit or circuits, the length of timerequired for the restoring depending upon the amplitude of the firstmovement and the speed of the restoring movement. Switching mechanism ofthis type is particularly suitable for use in connection with theelectric motor circuits disclosed in my copending applications SerialNo. 501,405 filed September 6, 1943, and Serial No. 508,425 filedOctober 30, 1943, now Patents No. 2,400,579 and No. 2,400,580respectively, both issued May 21, 1946, to which this applicationrelates back for all common subject matter.

In each of said applications there is more or less diagrammaticallyshown electric switching mechanism having a manually turnable memberwhich may be turned in one direction in order to cause plurality ofelectric motors to run in a forward direction, and which may be manuallyturned in the opposite direction to cause the motors to run in reverse.Moreover, the distance through which the member is manually turneddetermines the number of revolutions the motors will make before thecircuit is opened, one of the motors being mechanically connected toreopen the switch. The switching mechanism shown in Patent No. 2,400,580also includes means for closing an additional circuit whenever themanually turnable member is moved to either of its extreme positions.

While switches of the types shown in my aforesaid applications are inmany respects satisfactory, and fall within the scope of the inventionset forth in the present application, there is herein disclosed animproved form of switching mechanism which does not require slidingcontacts and in which standard quick make and break switches areemployed.

Another object of my invention is to incorporatein a device of thisnature indicating means which will inform the operator whether or notthe motors controlled by the switch have rotated the desired number ofrevolutions.

A still further object of my invention is to provide a unitaryassemblage of switching mechanism, an electric motor therefor andsuitable gearing connecting the motor to the mechanism.

Further objects and advantages will be apparent from the followingdescription considered in connection with the accompanying drawings,

2 which form a part of this specification, and of which:

Fig. 1 is a cross-sectional view of the switching mechanism, the drivingmotor therefore being shown diagrammatically;

Fig. 2 is a cross-sectional view taken on the line 2--2 of Fig. 1;

Fig. 3 is an end view of a portion of the device shown in Fig. 1, and istaken in the direction of the arrows 33;

Fig. 4 is a View, partially in cross section, of a portion of the deviceshown in Fig. 1;

Fig. 5 is a front view of the control knob and dial; and

Fig. 6 is a view similar to Fig. 5, but with the knob and dial removed.

Referring to the figures, reference character l0 designatesdiagrammatically a reversible electric motor. This motor drives a shaft46 through a suitable gear reduction 24. Shaft 46 carries a worm 58which meshes with a worm gear 50 mounted on a shaft 52 which isrotatably carried in an end wall of a switch housing 54.

The opposite end of shaft 52, which extends within the switch housing,carries a spur gear 58 which meshes with a similar gear 58 rotatablymounted on a shaft 60. This shaft is rotatably supported in a bracket 62adjacent to the front end of the switch housing 54.

Rigidly fixed to gear 58 are two or more pins 64 upon which is slidablymounted a collar 65. This collar surrounds a cylindrical cam member 68which is fixed to the inner end of shaft 60. The cam member is formedwith a cam groove 10 in its cylindrical surface. This groove is made upof two circular parallel portions, each of which extends somewhat lessthan 360 degrees around the cylinder, and a spiral portion 12 whichconnects one end of one circular portion with the opposite end of theother circular portion. The collar 66 carries a radially extending pin14, shown in Fig. 4., which projects into the cam groove 10, the collarand pin thus constituting a cam follower.

The outer circumference of the collar 6'6 is formed with an annulargroove 16 into which extends one end of a leaf spring 18, the other endof the spring being secured to the housing 54 by means of the bolt 80.

Located on opposite sides of the spring 18 are electric switches 82 and84. These switches may be of standard construction and consequently havenot been shown in detail. However, they are of the quick make and breakpush button or plunger type, having plungers 86 and 88, respectively,

which bear against opposite sides of the spring. These plungers areurged toward the spring by means of coil springs or the like included inthe switch mechanism and the arrangement is such that when. the plungeris forced inwardly against the force of the coil spring, the circuitthrough the switch is closed, and is opened when external pressure onthe plunger is relieved thus permitting the coil spring to force theplunger outwardly.

Suitably secured to the forward end of the shaft 60 is a manuallyturnable knob 90. Sui rounding the shaft 60 is a sleeve 92 to theforward end of which there is fixed aring 94. This ring is generallycircular, but is formed with a radially projecting lug 96 which isthreaded to receive set screw 98, as is shown more particularly in Figs.1 and 2. Rigidly secured to the shaft is a disc I00 having an outerdiameter such that it is substantially tangent to the threaded portionof the set screw 98, whereby the head of the set screw overlies the edgeof the disc. Consequently, if the set screw is loosened, the ring 00 andhence the sleeve 92 may be rotated with respect to the shaft 60 and thedisc I00, but tightening of the set screw serves to clamp all thesemembers together. The inner end of the sleeve 92 carries an arm I02,which is arranged to strike the plunger I04 on an electric switch I08 ofthe same type as switches 82 and 84. This switch is located directlybeneath the shaft 60 so that the arm I02 strikes the plunger when thearm is turned to a substantially vertical position. A pin I08 projectsinwardly from the bracket 62 of the switch housing and acts as a stop tolimit rotation of the arm I02 and hence the shaft 60, the pin stoppingthe rotation of these members when the arm actuates the switch I06.

Surrounding the sleeve 92 is a sleeve IIO to the forwarding end of whichis secured a ring II2. This ring is provided with a lug I I4, which issimilar to the lug 96 on ring 94, but has sufficient axial extent in aforward direction to overlie the rim 9t and abut against the disc I00. Aset screw H6 is threaded into the lug N4, the head of the screwcontacting the disc I00 so as to lock the ring H2 in adjusted positionwith respect to the disc. The inner end of the sleeve H0 is providedwith an arm II8 which is similar to arm I02, except that it has anaxially offset portion extending into the same radial plane as thatoccupied by the arm I02 in order that the arm IIB may contact theplunger I04 on the switch I06. The pin I08 acts as a stop for the armII8 as well as for the arm I02.

During operation of the device the set screws 98 and IIS remain tightand the arms I02 and H8 are firmly fixed with respect to each other andto the shaft 60 and consequently all these members turn as a unit whenthe knob 90 is rotated. However, the angular position of either armrelative to the other and to the shaft 60 may be adjusted by looseningthe proper set screw, whereupon the arm and the sleeve to which it isattached may be rotated relative to the shaft. In this way, the anglethrough which the shaft may be rotated before it is stopped by one orthe other of the arms contacting the pin I08 may be adjusted.

The rear end of shaft 60 extends through the rear wall of the casing andis provided with a knurle knob I20. A spring member I22 has one endsecured to the casing by means of the screw I24, while the other endbears against the knurled knob I20, as shown in Fig. 3. The mmpose ofthis is to provide resistance to the turning of the shaft 60 in orderthat the latter will not be turned accidentally, as by jarring or as aresult of frictional drag on the cam 68 resulting from rotation of thecam follower.

The front end of the casing 54 is provided with a transparent dial I24in front of which is arranged a transparent dial cover I26, both ofwhich are held in place by means of a snap ring I28. The dial I24 may beprovided with suitable calibrations, as is shown in Fig. 5. As hereshown, the dial is calibrated in engine speeds from 1200 to 3000 R. P.M. The annular portion I30 of the dial which carries the calibrations ispreferably made opaque except for the calibrations, so that the lightfrom the bulb I32 will clearly illuminate calibrations on the dial. Theportion I34 of the dial radially outside of the band I30 is transparent,so that the outer ends of indicators I36 and I38 are visibletherethrough. Indicator I36 is fixed to the shaft 60 so as to be rotatedby turning of the shaft and consequently it indicates the position ofthe shaft. Its outer visible end may have a triangle painted thereon, asshown in 6. Indicator I38 is secured to pinion 58 and hence rotates withthe cam follower so as to indicate the position of the latter. As shownin Fig. 6, the outer visible end of thisindicator may be formed as acircle.

Located in the lower part of the switch housing 54 is a plurality ofsignal lamps, one of which is designated by reference character I40 inFig. 1.

Each lamp is located in a separate compartment I42, each of which isprovided with a centrally located passage I44 and an offset passage I",the outer ends of which are visible through the transparent portion ofthe dial. A slidable shun ter, movable by means of a handle I48, ispro-- vided for closing the passages I44 when desired in order thatdirect rays from the lamps will not be visible, as such rays woulddestroy the night vision of the pilot. While these signal lights areconveniently located in the switch housing, they form no part of thepresent invention, and hence further detailed description thereof is notbelieved to be necessary.

The above-described device operates as follows:

With the switch parts in the positions shown in the drawings, namelywith the indicator arms I30 and I38 parallel to each other and standingat, 2100 on the dial, the engine or engines of the aircraft are rotatingat 2-100 R. P. M. If, for instance, the pilot wishes to increase thespeed of the engine or engines to 2400 R. P. he turns the knob in aclockwise direction until the indicator I36, which is secured to theshaft 00, stands at 2400 on the dial. Rotation of the shaft 60 alsorotates the cam 08. Consequently, the pin 'M,which is located in thecenter of the spiral portion of the cam groove I0 when the indicatorsI36 and axially with respect to the cam, inasmuch as the collar 06cannot be rotated because of the irreversible worm gearing including thegears 08 and 50. Rotation of the-shaft 50 in a clockwise direction asviewed in Fig. 5, causes the pin "I4 and the collar 65 to be displacedaxially on the pins '64 towards the right as viewed in Fig. 1. This Inturn displaces the upper end of the leaf spring "I8 towards the rightand depresses the plunger '00 of switch 84. Acircuit is thus completedthrough the switch which, acting through a suitable system of relays,for instance, as disclosed in my Patent No. 2,400,580, causes rotationof the electric motor ID, as well as the synchroridus rota- I38 areparallel, is displaced tion of similar electric motors which change theadjustment of the governors which control the s a ofthe engines of theaircraft. The motor fo tates in, a proper direction so as to rotate tcollar [56 in the same direction that the cam was, rotated. When themotor has rotated a sufli cient number of revolutions to turn the collarthtough the same angle as the cam was grigipaliyrotated, thepin I4 willagain occupy the center of the spiral portion 12 of the cam slot,and'hence the collar 66 will be displaced axially to the left on thepins 64 to its intermediate or neutral position. Hence, the spring 18will be restored'to its neutral position and the plunger 83 otith'e.switch 84 released so as to open the switch and stop. the electric.motors. Rotation of the collar 66 also rotates the indicator I38 throughthe same angle that the shaft 60 was originally rotated, and hence itwill come to rest parallel with the indicator I66. Meanwhile, the motorsassociated with the governors have rotated the same number ofrevolutions as the switch motor, and the governors are so designed thatthis causes an increase in engine speed from 2100 R. P. M. to 2400 R. P.M.

Obviously, the further the cam 68 is turned by the knob 90, the greaterthe number of revolutions required of the electric motor I0 to drive thecam follower through a like angle, and hence the greater the number ofrevolutions performed by the motors associated with the engine governorsand the greater the speed change effected thereby.

If for any reason there should be a failure in the electrical systemwhich prevents the electric motors from starting or performing theproper number of revolutions, this would at once be apparent to thepilot, inasmuch as the indicator arm I38 would not move at all, or wouldnot move all the way into parallelism with the indicator I36 in the newposition of the latter. In other words, the indicator I36 designates theengine speed desired by the pilot, while the indicator I38 designatesthe actual engine speed.

If it is desired to reduce the speed of the engines, the knob 90 isturned in the opposite direction until the indicator I36 stands at thedesired speed on the dial. This turns the cam 63 in the oppositedirection from that previously described, and consequently, the pin M inmoving out of the spiral portion of the slot displaces the collar 66 tothe left. Hence, the spring I8 is moved to the left, as viewed in Fig.1, thus depressing the plunger 86 of switch 82, which closes a circuitthrough this switch. Closure of this switch causes the electric motorsto operate in the reverse direction from that previously described. Themotors associated with the engine governors hence alter the governorsettings so as to reduce the engine speed, while the motor I0 drives thecollar 66 so as to restore the pin I4 to the center of the spiralportion I2 of the cam slot. This in turn restores the spring 18 to itscentral position, thus opening the switch 82 and stopping the electricmotors.

In accordance with the circuits disclosed in my aforesaid Patent No.2,400,580, it is possible to individually operate the electric motorsassociated with the engine governors so as to cause the differentengines in a multi-engine ship to rotate at different speeds. Suchcontrol is by individual switches usually located in the flightengineers compartment. However, it is desirable that the pilot be ableto resynchronize all of the engines at either their maximum or minimumspeeds, and this may be done by means of a single switch which is closedwhenever the knob is turned to either of its limit positions. Thus, ifthe knob 90. is turned as far as it will go in a clockwise direction,the arm H8 strikes the pin I08, thus, preventing further rotation of theshaft and knob. At the same time, the arm I I8 strikes the plunger we ofthe switch Hi6. Meanwhile, rotation of the cam 60, has displaced thecollar 66. to, the. right, thus closing the switch 84 and the closure ofthe switch I06 at the same time the switch as is closed results in thedifferent engines being synchronized at the maximum speed. Likewise, ifthe. knob 90 is turned all the way in a counter-clockwise direction, thearm i0-2 strikes the pin tits so as to. stop further rotation, and thearm also actuates the switch I06. The electric circuits are such that ifthe switch I06 is closed at the same time the switch 82 is closed, theengines are synchronized at their minimum speed. A complete descriptionof the circuits for accomplishing this is given in my aforesaid PatentNo. 2,400,580, but inasmuch as these circuits form no part of theinvention as herein claimed, they have not been described.

As previously explained, the maximum arc through which the shaft 60 maybe rotated is adjustable by means of the arms I02 and H8. Thus, if theswitch were to be used on an aircraft employing engine having a maximumspeed of, for instance, 2800 R. P. M., the arm II8 would be so adjustedas to strike the stop pin I 08 and to actuate the switch I06 when theindicator I36 stands at 2800 on the dial. Likewise, if the minimum speedof the engines was, for instance, 1500 R. P. M., the arm I02 would be soadjusted as to stop the rotation of the shaft and to actuate the switchI06 when the indicator I36 stands at 1500 on the dial. In this way, thedial may be calibrated for the greatest range of engine speeds likely tobe encountered and may still be used on ships having a lesser range ofengine speeds.

While I have shown and described one more or less specific embodiment ofmy invention, it is to be understood that this has been done for thepurpose of illustration only and is not to be considered as limiting thescope of my invention which is to be determined from the appendedclaims.

What I claim is:

1. In a switching mechanism, a rotatably mounted cam, a cam followerassociated therewith, means for mounting said follower for axial androtational movement with respect to said cam, said cam having a profileincluding two axially spaced prolonged dwells connected by an inclinedportion, said follower having a neutral position at the center of saidinclined portion whereby rotation of the cam in one direction initiallydisplaces said follower axially in one direction from the neutralposition and thereafter retains the follower in the displaced positionand rotation of the cam in the opposite direction initially displacessaid follower axially in the opposite direction from said neutralposition, means for rotating said follower in the proper direction toreestablish the original relative rotative position of the follower andcam whereby to return said follower to its neutral axial position, apair of quick action electric switches, means responsive to axialdisplacement of said follower in one direction for actuating one of saidswitches and responsive to axial displacement of said follower in theopposite direction for actuating the other 01 said switch, thelast-mentioned means restoring whichever switch has been actuated to itsoriginal condition upon return of said follower to its neutral position,means for preventing either said cam or said follower from impartingrotary motion to the other, a pair of arms rotatable with said cam andindividually rotatably adjustable with respect to said cam, and stopmeans engageable by said arms to thereby establish opposite individuallyadjustable extreme positions for said cam.

2. The switching mechanism as set forth in claim 1 including a quickaction electric switch arranged to be actuated by either of said armswhen the respective arm engages said stop means.

ERIC C. WAHLBERG.

REFERENCES CITED The following referenices are of record in the file ofthis patent:

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